The present invention is especially useful in tactical type missiles or intercept systems, such as air-to-air missiles and the like. The major problem that occurs in these missiles or systems is the launching of missiles when it is impossible for the missile to intercept the designated target because of the targets orientation, speed, distance, etc. In some prior art systems the launch vehicle has an airborne intercept type radar with associated computer mounted thereon which can determine some of the required parameters so that the number of missiles launched with no chance of intercepting the target is greatly reduced. However, many airborne and surface launch vehicles do not have the computer or even the radar, so a simplified launch envelope computation system in the missile is desirable.